Exterior stucco or cement plaster, as it is commonly known, is installed on commercial as well as residential buildings and can be applied over a variety of substrates such as masonry as well as framed/sheathed wall assemblies. Depending upon the type of substrate, an intervening layer of a water resistive barrier and lath or plaster base, which serves as a mechanical key for the stucco, is applied prior to the application of the stucco.
There are two common types of stucco which are commonly referred to as One Coat Stucco which generally consists of a ⅜ to ½ inch thick stucco and Three Coat or traditional stucco which generally consists of ½ to ¾ inch thick stucco. The stucco is either hand troweled or spray applied to the substrate or lath (if used). Trim accessories, also known in the building and construction industry as trim bead, which are fabricated from metal or plastic, are used in conjunction with stucco to serve as a gauge for the stucco thickness and/or as a termination or stopping point for the stucco. A finish coat or paint/coating is applied over the dry/cured stucco to provide the final appearance.
Thermal insulation, when used with stucco clad walls, is most commonly achieved by installing one of several types in the stud or wall cavity. In some cases, limited thicknesses (generally no greater than 1½″) of a thermal insulation board, which is generally a foam plastic such as Expanded Polystyrene, is installed continuously over the substrate prior to the application of the lath. Historically, continuous thermal insulation board has been used more often with the One Coat Stucco systems than with Three Coat Stucco systems.
Due to recent energy codes such as the IECC (International Energy Conservation Code), as well as standards such as ASHRAE (American Society of Heating, Refrigerating, and Air-Conditioning Engineers), there is an increasing demand in many cases to use Stucco with continuous thermal insulation applied over the substrate at greater thicknesses than the 1½″ which has traditionally been used in the past. In fact, continuous insulation thicknesses of 4″ or more may be needed to satisfy existing or anticipated energy code requirements. As the thickness of the continuous insulation board increases, it can change the geometry, profile, complexity and detailing of stucco wall assemblies specifically as it relates to satisfying conditions such as fire requirements, drainage, and final aesthetic appearance. Trim accessories, originally intended for use with stucco that did not contain continuous insulation or possibly accommodated thinner (1½″ thick or less) continuously insulated systems often can not accommodate the thicker continuously insulated systems. Current commercially available trim accessories, which for various technical as well as aesthetic reasons, do not sufficiently satisfy the thicker continuous insulation systems. As a result, there is a need to develop a new type of trim accessory that will better accommodate continuously insulated stucco systems.